The St. Louis Cathedral is a beautiful cathedral and an icon of New Orleans. It is filled with New Orleans history and it was interesting to walk through. I am not personally Roman Catholic, but I enjoyed looking at the architecture and the stained glass windows representing the life of Saint Louis the King of France who was involved in the Crusades.
One of the employees/volunteers in the cathedral showed my children some of the tiles in the floor that had fossils in them. The children enjoyed that. Also when we walked in to the cathedral someone was play the pipe organ; it was beautiful.
If you visit New Orleans you need to make at least a brief visit to the Cathedral to enjoy the history and architecture.